Schottky diodes have been widely used in high frequency integrated circuits because of their unique capabilities for fast switching with a low voltage drop. Many semiconductor devices have employed Schottky junction diode devices because of their unique characteristics. Instead of a semiconductor to semiconductor junction as a barrier in a conventional semiconductor diode, the Schottky junction diode device uses a metal to semiconductor junction, also known as Schottky junction, as its barrier. Since conventional complementary metal oxide semiconductor (CMOS) integrated circuits generally do not employ Schottky junction diodes, Schottky junction diodes are not known to be available in standard CMOS semiconductor fabrication processes. Schottky junction diodes of the prior art require specialized semiconductor fabrication processes.
FIG. 1 is an elevational cross-sectional drawing illustrating a conventional Schottky junction diode device 100 formed in silicon (Si) in accordance with the prior art. Device 100 includes a p− substrate 102, an n− well 104 and a p− well 106. A metal-containing layer 108 is formed in contact with n− well 104 to form a Schottky junction 110 at the interface between the metal-containing layer 108 and the silicon of n− well 104. The p− well 106 is contacted or substantially contacted to n− well 104 at interface 112. A substrate contact 114 is provided for the device at p− well 106. Substrate contact 114 is used for biasing the substrate. One or more n− well contacts 116a, 116b are provided at n− well 104. The Schottky junction diode is defined between metal-containing layer 108 and n− well contact 116a or 116b. A drawback associated with this conventional approach is that there is a relatively high capacitance created between the wells 104 and 106 which limits the performance of the Schottky junction diode device 100.
Therefore, there is a need in the art to improve Schottky junction diode devices so that they may exhibit higher performance and be fabricated in conventional CMOS process environments.